This page gives information on the maintenance issues at ING.
Optical maintenance
Plans for maintenance
With optical maintenance the monthly work is meant, which should be carried out by an optical expert or people assigned by him. The main work on the optical maintenance is the quality control of the optics, which means that the optical expert has to visit the site where the optical elements are in a regular basis. The maintenance procedure contains taking measurements of the different parameters of the optical components, analysing the results and taking the necessary action based on the investigation. Naturally, feedback from the observers is needed also in order to monitor thoroughly the quality of the optical components. The way of doing this could be to contact the optical expert by e-mail or use the fault database or the filter database. All of the mentioned procedures have to be documented, stored and made available for the competent staff. These are the links, where the optical maintenance related information could be find:
It is useful to create a schedule for the optical maintenance of the different optical components. Together with the astronomers the following schedule have been set for the optical maintenance:
Main mirrors
|
Components |
Inspection |
Measure |
Clean - CO2 |
Clean - vapour washing | Aluminising |
|
WHT primary mirror |
visual inspection every week from AP3 |
measure reflectivity 1 month |
1 month |
only if necessary (massive contamination, stains, etc), probably once in a year | 2-3 years, depending on the measurements and surface investigation |
|
WHT secondary mirror |
visually every week |
measure reflectivity 6 months |
6 months |
only if necessary (massive contamination, stains, etc) | 2-3 years, depending on the measurements and surface investigation |
|
WHT tertiary mirror |
visually every week |
measure reflectivity 6 months |
6 months |
only if necessary (massive contamination, stains, etc) | 2-3 years, depending on the measurements and surface investigation |
Other optical elements
|
Components |
Measure |
Inspect throughput |
Clean |
|
Diffraction gratings |
1 year |
3 months |
never |
|
Collimators |
1 year |
3 months |
as required |
|
Filters in spectrographs |
2 year |
3 months |
6 months |
|
Dichroics in spectrographs |
2 years |
3 months |
6 months |
|
Filters in imaging mode |
2 years |
6 months |
on use/as required |
|
Liquid CuSO4 filters |
3 months |
3 months |
refill as required |
|
Derotators |
1 year |
3 months |
as required |
|
CCD's |
6 months |
at change |
|
|
CCD windows |
never |
at change |
at change |
This document is partly based on this document: optical_maintenance_report_2002